SEATTLE - An 11-month investigation by the U.S. Justice Department has found the Seattle Police Department "engages in a pattern of unnecessary and excessive force" in "violation of the Fourth Amendment," federal officials announced Friday.

Assistant Attorney General Thomas Perez, who heads the Justice Department's Civil Rights Division, flew to Seattle on Thursday to announce the findings at a news conference alongside U.S. Attorney Jenny Durkan.

According to the Justice Department report, Seattle police use force in an "unconstitutional manner nearly 20 percent of the time."

The investigation was launched last spring following the deadly shooting of a homeless Native American woodcarver and other incidents of force used against minority suspects.